1. Field of the Invention
The present invention relates to a storage system that includes a storage device, an external storage device, and a management computer. In particular, the present invention relates to a method of allocating the logical volume of the external storage device to the virtual logical volume of the storage device by the management computer.
2. Description of the Related Art
In recent years the volume of data handled by computer systems has increased dramatically. Also, the management of storage systems storing the data has become more complex.
A storage device provides storage area to a host computer in units referred to as a logical volume. Conventionally, the storage device allocated arbitrary logical volumes within the storage device to the host computer. However, in recent years the storage administrators are demanding storage devices with system configurations capable of increasing the access to data performance.
Therefore Japanese Patent Application Laid-open No. 2005-062941 discloses a method in which the management computer of a storage system reports the I/O performance of the port of the storage system connected to the host computer. By referring to this report, the administrator can identify the storage resource on which the I/O load is concentrated.
Also, conventionally a storage device connected to a host computer allocates physical resources to a logical volume. When the capacity of the physical disk of the storage device is used up, the storage device connects a second storage device to the host computer, and allocates the logical volume of the second storage device to the host computer. However, when connecting the host computer to the second storage device, work is required to physically connect the host computer and the second storage system, and work is required to set the path to the logical volume of the second storage device. Therefore, a method of allocating the logical volume is required that can further reduce the effort required for these operations.
Therefore Japanese Patent Application Laid-open No. 2004-005370 discloses a method of transferring an I/O request from a host received by a first storage device to a second storage device connected to the first storage device.
According to Japanese Patent Application Laid-open No. 2005-062941, in order for the storage device to allocate appropriate physical resources to the logical volume, it is possible to obtain the port performance data of the storage device connected to the host computer, and report the I/O performance of each physical resource.
Also, according to Japanese Patent Application Laid-open No. 2004-005370, it is possible to connect the first storage device and the second storage device, and transfer I/O requests from the host computer to the first storage device to the second storage device.